Sandwich, MA to Providence, RI is a LONG way for a day sail. I went from Sandwich to South Dartmouth, MA in about 3.5 h at 6-6.5 kts. South Dartmouth is about 30% of the way there, so you may be looking at 12h + easily at 6kts.

Anyway you can get through the Canal the day before and layup in Onset or Marion?

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